Warehousing and distribution facilities have grown in importance in the supply chain in recent years. In such facilities, large warehouses are used to collect and store many types of goods at a central location for shipment by truck to one or more locations, typically retail locations. Goods may be stored in the warehouse by pallet load or individually, and goods may be shipped either by uniform pallet, mixed pallet, or otherwise. To maximize efficiency, goods are often stored in vertical rack based systems, multiplying the amount of goods that can be stored in a given amount of square footage.
Some systems, sometimes known as high density or ultra-high density rack systems, store pallets of goods in a large, multi-layer rack. Pallets are stored according to known identifiers such as SKU numbers or the like and kept track of by a computer-based system. As pallets of goods are stored in the system, the related identifiers are noted and stored in a computer memory or the like so that when the goods are desired, they can be retrieved.
Automated systems of this type use carts that place the goods in the rack and retrieve the goods when desired. Such automated systems provide efficiency in terms of floor space usage, as well as quick loading and retrieval of goods with low need for manual attention or monitoring. Various cart-based rack systems have been proposed, with one or more carts that travel from a staging area to a storage area to place and retrieve goods. Existing cart-based systems and related rack structures provide acceptable storage capabilities. However, as rack systems become larger, improvement in cart functionality and efficiency, as well as in rack design to handle larger systems, would be welcome.